In the past a bread cooling system of this type has been operated by two conveyor chains which run the length of the apparatus, one conveyor being located at each side of the line of racks carrying the bread. The conveyor chains carry rack control arms--one for each side of each rack--projecting at right angles to the conveyor. A spigot projecting from each side of each rack passes through a longitudinal slot in the rack control arm and carries at its end a roller which runs on a rail along the conveyor.
The system outlined above has certain disadvantages. In the first place the long conveyor chains require a considerable amount of take-up facility. Secondly the rack control arms, when they are at the ends of the conveyors and the chain links to which they are attached are rounding the sprockets, give heavy loadings on the chains, magnifying the effects of clearance in the chains and between the chains and sprockets. Furthermore, in order to provide vertical movement to the racks at the end of the conveyor where loading and unloading takes place, the spigots on the racks move along the slots during this movement, and this in turn means that a constant sprocket speed produces a faster rack movement at the top and bottom of its vertical run: this makes loading and unloading more difficult. Moreover, as the control arms of necessity project outwardly beyond the racks at the ends of the conveyor, as the chains are passing round the sprockets, any conveyors operating at right angles to the cooler conveyor for the purpose of loading or offloading the cooler conveyor must be placed outside the path of travel of the control arms. This means that both loading and unloading requires a two-stage loader and unloader.